With MRI, a high field magnet, typically superconducting, is arranged in a torus configuration (like a donut) and with the patient lying down inside the magnet on a table where the magnetic field allows a pulsed and sequenced magnetic and EM field to probe the body to produce images, which allow the trained radiologist to determine with high probability the anatomy of the patient. MRI is sometimes performed using contrast agents introduced to the patient to provide even better contrast between different tissue types. MRI techniques are very good at detecting the anatomical location of different diseases, for example, tumours.
In U.S. Pat. No. 5,735,278 (Hoult et al) issued Apr. 7, 1998, disclosed a medical procedure where a magnet is movable relative to a patient and relative to other components of the system. The moving magnet system allows intra-operative MRI imaging to occur more easily in neurosurgery patients, and has additional applications for liver, breast, spine and cardiac surgery patients.
In Published PCT Application WO07147233A1 of the present Applicants published Dec. 27, 2007 and entitled ROTATABLE INTEGRATED SCANNER FOR DIAGNOSTIC AND SURGICAL IMAGING APPLICATIONS is disclosed an improvement to the above patent in which an additional rotational movement of the magnet is allowed.
A scanning system is known in which the patient is moved from an X-ray imaging system to an MR imaging system by transferring the patient from one imaging system to the other, for example, on a moveable table. The MR scanner is used to provide information complementary to that obtained using X-ray. It can be used, for example, to perform a baseline assessment prior to intervention as well as to perform a post-intervention assessment. Such an assessment may include perfusion and viability studies of the heart or of the brain.
U.S. Pat. No. 5,713,357 (Meulenbrugge) issued Feb. 3, 1998 and related U.S. Pat. No. 5,807,254 both of Phillips shows a combination of an X-ray system and an MRI system. The system is not for intra-operative uses and the magnet is not a cylinder. The magnet is not moved. The X-ray is moved side to side in FIG. 2. The patient is moved in FIG. 1.
U.S. Pat. No. 6,101,239 (Kawasaki) issued Aug. 8, 2000 to Hitachi provides an X ray and MRI operating simultaneously at the same location and methods to operate them in a timed manner to avoid interference. However this arrangement is not suitable for interventions by the medical team since the presence of the machines restricts access to the patient.
U.S. Pat. No. 6,385,480 (Bachus) issued May 7, 2002 of Siemens discloses what they call an angio-MR system where the radiographic angio-system cooperates with the MR system. There is provided a moving patient table which transfers the patient from the X-ray system at one location to the MRI at a second location.
US Patent Application 2006/0239524 (Desh) published Oct. 26, 2006 of Siemens relates to diagnosis and treatment of cardiac diseases using MRI and X-ray. This is directed to a method of combining the images to analyze the diagnosis.
U.S. Pat. No. 6,975,895 (Pelc) issued Dec. 13, 2005 to Leland Stanford University provides a modified X ray tube for use in magnetic fields of an MRI system.
U.S. Pat. No. 6,812,700 (Fahrig) issued Nov. 2, 2004 of Leland Stanford University discloses a related system in which the perturbations in the magnetic field of the MRI caused by the X-ray system are compensated.
U.S. Pat. No. 6,658,085 (Sklebitz) issued Dec. 2, 2003 of Siemens discloses a system in which current for the coils generating the magnetic field of the MRI is calculated to reduce stray fields in the area of the X-ray system.
U.S. Pat. No. 5,865,780 (Tuite) issued Feb. 2, 1999 of SDGI Holdings discloses a device for engaging and holding the body of the patient during procedures in MRI and X-ray imaging.
U.S. Pat. No. 4,595,899 (Smith) issued Jun. 17, 1986 to Leland Stanford University provides an MRI system.
U.S. Pat. No. 5,099,846 (Hardy) issued Mar. 31, 1992 relates to combining images from different imaging modalities and is primarily about the software for combining the images such as X-ray and NMR.
U.S. Pat. No. 6,754,519 (Hefetz) issued Jun. 22, 2004 to Elgems discloses two imaging systems such as CT and MRI where the two systems are mounted on a common rail system for rolling movement from a common position to a spaced position.
U.S. Pat. No. 5,291,890 (Cline) issued Mar. 8, 1994 to GE discloses a patient heat treatment system where the heat is detected using an MRI.
U.S. Pat. No. 6,961,606 (DeSilits) issued Nov. 1, 2005 to Phillips discloses two imaging systems such as CT and PET where the two systems are mounted on a common rail system for rolling movement from a common position together for common scanning of the patient to a spaced apart position.
German patent application 39 31 854 of Muller published Apr. 4, 1991 discloses an NMR apparatus using a laser coagulation stereotactic system.
Japanese application 05344964 of Toshiba shows a combination of an X-ray system and an MRI system. This is application is filed only in Japan and provides what is apparently a crude system.
Japanese patent application 4183446 published Jun. 30, 1992 by Res Dev Corp of Japan discloses the use of MRI and X-Ray in a common apparatus.
One element which must be designed for use with a combined imaging system of the type described above is that of the patient support table and components for providing support which are used during the procedures in the MR and X-ray imaging.
Typically during imaging and non-surgical intervention, the patient is merely resting on a suitable support surface which can be just the table or a table with extensions for holding the head or other extremities.
However during surgical procedures it is necessary in many cases to provide structural support components which hold a body part such as the head of the patient stationary during the imaging and during the procedures which follow the imaging.
Such structural support components when used in X-ray imaging systems are typically formed from a material commonly known as Novotex which is supplied by Pro-Med Instruments Inc, Manufacturing and Distribution of Surgical Products and is formed of a phenolic resin reinforced by cotton fibers. This is selected because it has a low absorption factor for X-rays which is measured as an Aluminum equivalence factor and this is typically of the order of 4 mm for 10 mm of material. Usually devices require much thicker material, as much as 25 to 30 mm which takes the Aluminum equivalence factor to 8 to 10 mm.
Such materials including particularly the Novotex material are considered to be MR compatible in that they are non-ferromagnetic so that they can be placed in the magnetic field and they are non-electrically conductive so that they do not affect the radio frequency fields. Novotex also provides the necessary adequate physical characteristics including strength and hardness so that it is to be expected that Novotex can be used for constructions to be used in both MR and X-ray imaging.
In PCT application WO 2010/111772 published Oct. 7, 2010 by the present assignees is disclosed a head clamp for use in a combined MR and X-ray imaging system of the type described above. However up to now it has not been possible with a head clamp to meet the requirements of radio-lucence required by FDA where the attenuation of the device when present in the X-ray image must be less than a factor of 2.3 mm of aluminum equivalent, that is the attention must be less than that of 2.3 mm of aluminum.
All publications, patents, and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference.